The following meanings for the abbreviations used in this specification apply:    ADC Analogue-digital converter    AGC Automatic gain control    AP Access point    CA Cooperation area    CC Channel component    CDM Code division multiplex    CoMP Cooperative multipoint transmission    CSI Channel state information    eNB enhanced Node B    FDM Frequency division multiplex    IQ Components of a signal in base band representation    ISD Inter site distance    JT Joint transmission    LTE Long Term Evolution    LTE-A LTE-Advanced    MIMO Multiple-input multiple-output    MSE Mean square error    MU Multi-user    OFDM Orthogonal frequency division multiplex    RE Resource element    RS Reference signal    RSRP Reference signal received power    Rx Reception    SI Study item    SINR Signal to Interference plus Noise Ratio    TDM Time division multiplex    Tx Transmission    UE User equipment    WB Wideband
Embodiments of the present invention relate to mobile radio system concepts like 3GPP LTE, LTE-A and especially future optimizations for CoMP. In the EU founded project Artist 4G advanced CoMP is being investigated for downlink transmission and especially a novel interference mitigation scheme called IFM-A has been developed based on joint transmission (JT) CoMP. This novel interference mitigation framework has been developed promising significant performance gains over that so far reported from 3GPP CoMP SI. For example, for similar simulation assumptions more than 200% gain seems to be possible for the interference migration (IFM-A) framework compared to a 4×2 MU MIMO scenario as reference. Both cases are for ideal channel estimation, but a higher sensitivity can be expected for the CoMP system.
For practical JT CoMP systems accurate channel estimation is very important and for IMF-A this is especially true for weak channel components. It has been found that any improvement in channel estimation will help to increase system level performance.
Therefore, a highly sophisticated CSI estimation and feedback concept will be required to leverage a significant part of the above mentioned performance gains and this is true even for low to very moderate mobile speed.
Hence, it is desirable to significantly improve CSI estimation quality, especially with respect to the channel estimation of weak channel components. Simultaneously a small to moderate reference signal overhead should be kept.